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icinga2/doc/3-monitoring-basics.md

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Monitoring Basics

This part of the Icinga 2 documentation provides an overview of all the basic monitoring concepts you need to know to run Icinga 2.

Hosts and Services

Icinga 2 can be used to monitor the availability of hosts and services. Hosts and services can be virtually anything which can be checked in some way:

  • Network services (HTTP, SMTP, SNMP, SSH, etc.)
  • Printers
  • Switches / Routers
  • Temperature Sensors
  • Other local or network-accessible services

Host objects provide a mechanism to group services that are running on the same physical device.

Here is an example of a host object which defines two child services:

object Host "my-server1" {
  address = "10.0.0.1"
  check_command = "hostalive"
}

object Service "ping4" {
  host_name = "localhost"
  check_command = "ping4"
}

object Service "http" {
  host_name = "localhost"
  check_command = "http_ip"
}

The example creates two services ping4 and http which belong to the host my-server1.

It also specifies that the host should perform its own check using the hostalive check command.

The address custom attribute is used by check commands to determine which network address is associated with the host object.

Host States

Hosts can be in any of the following states:

Name Description
UP The host is available.
DOWN The host is unavailable.

Service States

Services can be in any of the following states:

Name Description
OK The service is working properly.
WARNING The service is experiencing some problems but is still considered to be in working condition.
CRITICAL The service is in a critical state.
UNKNOWN The check could not determine the service's state.

Hard and Soft States

When detecting a problem with a host/service Icinga re-checks the object a number of times (based on the max_check_attempts and retry_interval settings) before sending notifications. This ensures that no unnecessary notifications are sent for transient failures. During this time the object is in a SOFT state.

After all re-checks have been executed and the object is still in a non-OK state the host/service switches to a HARD state and notifications are sent.

Name Description
HARD The host/service's state hasn't recently changed.
SOFT The host/service has recently changed state and is being re-checked.

Using Templates

Templates may be used to apply a set of identical attributes to more than one object:

template Service "generic-service" {
  max_check_attempts = 3
  check_interval = 5m
  retry_interval = 1m
  enable_perfdata = true
}

object Service "ping4" {
  import "generic-service"

  host_name = "localhost"
  check_command = "ping4"
}

object Service "ping6" {
  import "generic-service"

  host_name = "localhost"
  check_command = "ping6"
}

In this example the ping4 and ping6 services inherit properties from the template generic-service.

Objects as well as templates themselves can import an arbitrary number of templates. Attributes inherited from a template can be overridden in the object if necessary.

Apply objects based on rules

Instead of assigning each object (Service, Notification, Dependency, ScheduledDowntime) based on attribute identifiers for example host_name objects can be applied.

apply Service "ping4" {
  import "generic-service"

  check_command = "ping4"

  assign where "generic-host" in host.templates
  ignore where host.address == ""
}

In this example the ping4 service will be created as object for all hosts importing the generic-host template. If the address attribute is not set, the host will be ignored.

Groups

Groups are used for combining hosts, services, and users into accessible configuration attributes and views in external (web) interfaces.

Group membership is defined at the respective object itself. If you have a hostgroup name windows for example, and want to assign specific hosts to this group for later viewing the group on your alert dashboard, first create the hostgroup:

object HostGroup "windows" {
  display_name = "Windows Servers"
}

Then add your hosts to this hostgroup

template Host "windows-server" {
  groups += [ "windows" ]
}

object Host "mssql-srv1" {
  import "windows-server"

  vars.mssql_port = 1433
}

object Host "mssql-srv2" {
  import "windows-server"

  vars.mssql_port = 1433
}

This can be done for service and user groups the same way. Additionally the user groups are associated as attributes in Notification objects.

object UserGroup "windows-mssql-admins" {
  display_name = "Windows MSSQL Admins"
}

template User "generic-windows-mssql-users" {
  groups += [ "windows-mssql-admins" ]
}

object User "win-mssql-noc" {
  import "generic-windows-mssql-users"

  email = "noc@example.com"
}

object User "win-mssql-ops" {
  import "generic-windows-mssql-users"

  email = "ops@example.com"
}

Group Membership Assign

If there is a certain number of hosts, services or users matching a pattern it's reasonable to assign the group object to these members. Details on the assign where syntax can be found [here]

object HostGroup "mssql" {
  display_name = "MSSQL Servers"
  assign where host.vars.mssql_port
}

In this inherited example from above all hosts with the var mssql_port set will be added as members to the host group mssql.

Time Periods

Time Periods define time ranges in Icinga where event actions are triggered, for example whether a service check is executed or not within the check_period attribute. Or a notification should be sent to users or not, filtered by the period and notification_period configuration attributes for Notification and User objects.

Note

If you are familar with Icinga 1.x - these time period definitions are called legacy timeperiods in Icinga 2.

An Icinga 2 legacy timeperiod requires the ITL provided template legacy-timeperiod.

The TimePeriod attribute ranges may contain multiple directives, including weekdays, days of the month, and calendar dates. These types may overlap/override other types in your ranges dictionary.

The descending order of precedence is as follows:

  • Calendar date (2008-01-01)
  • Specific month date (January 1st)
  • Generic month date (Day 15)
  • Offset weekday of specific month (2nd Tuesday in December)
  • Offset weekday (3rd Monday)
  • Normal weekday (Tuesday)

If you don't set any check_period or notification_period attribute on your configuration objects Icinga 2 assumes 24x7 as time period as shown below.

object TimePeriod "24x7" {
  import "legacy-timeperiod"

  display_name = "Icinga 2 24x7 TimePeriod"
  ranges = {
    "monday"    = "00:00-24:00"
    "tuesday"   = "00:00-24:00"
    "wednesday" = "00:00-24:00"
    "thursday"  = "00:00-24:00"
    "friday"    = "00:00-24:00"
    "saturday"  = "00:00-24:00"
    "sunday"    = "00:00-24:00"
  }
}

If your operation staff should only be notified during workhours create a new timeperiod named workhours defining a work day from 09:00 to 17:00.

object TimePeriod "workhours" {
  import "legacy-timeperiod"

  display_name = "Icinga 2 8x5 TimePeriod"
  ranges = {
    "monday"    = "09:00-17:00"
    "tuesday"   = "09:00-17:00"
    "wednesday" = "09:00-17:00"
    "thursday"  = "09:00-17:00"
    "friday"    = "09:00-17:00"
  }
}

Use the period attribute to assign time periods to Notification and Dependency objects:

object Notification "mail" {
  import "generic-notification"

  host_name = "localhost"

  command = "mail-notification"
  users = [ "icingaadmin" ]
  period = "workhours"
}

Commands

Icinga 2 uses three different command object types to specify how checks should be performed, notifications should be sent and events should be handled.

Environment Variables for Commands

Please check Runtime Custom Attributes as Environment Variables.

Check Commands

CheckCommand objects define the command line how a check is called.

CheckCommand objects require the ITL template plugin-check-command to support native plugin based check methods.

Unless you have done so already, download your check plugin and put it into the PluginDir directory. The following example uses the check_disk plugin shipped with the Monitoring Plugins package.

The plugin path and all command arguments are made a list of double-quoted string arguments for proper shell escaping.

Call the check_disk plugin with the --help parameter to see all available options. Our example defines warning (-w) and critical (-c) thresholds for the disk usage. Without any partition defined (-p) it will check all local partitions.

Define the default check command custom attribute disk_wfree and disk_cfree freely definable naming schema) and their default threshold values. You can then use these custom attributes as runtime macros on the command line.

The default custom attributes can be overridden by the custom attributes defined in the service using the check command disk. The custom attributes can also be inherited from a parent template using additive inheritance (+=).

object CheckCommand "disk" {
  import "plugin-check-command"

  command = [
    PluginDir + "/check_disk",
    "-w", "$disk_wfree$%",
    "-c", "$disk_cfree$%"
  ],

  vars.disk_wfree = 20
  vars.disk_cfree = 10
}

The host localhost with the service disk checks all disks with modified custom attributes (warning thresholds at 10%, critical thresholds at 5% free disk space).

object Host "localhost" {
  import "generic-host"

  address = "127.0.0.1"
  address6 = "::1"
}

object Service "disk" {
  import "generic-service"

  host_name = "localhost"
  check_command = "disk"

  vars.disk_wfree = 10
  vars.disk_cfree = 5
}

Notification Commands

NotificationCommand objects define how notifications are delivered to external interfaces (E-Mail, XMPP, IRC, Twitter, etc).

NotificationCommand objects require the ITL template plugin-notification-command to support native plugin-based notifications.

Below is an example using runtime macros from Icinga 2 (such as $service.output$ for the current check output) sending an email to the user(s) associated with the notification itself ($user.email$).

If you want to specify default values for some of the custom attribute definitions, you can add a vars dictionary as shown for the CheckCommand object.

object NotificationCommand "mail-service-notification" {
  import "plugin-notification-command"

  command = [ SysconfDir + "/icinga2/scripts/mail-notification.sh" ]

  env = {
    "NOTIFICATIONTYPE" = "$notification.type$"
    "SERVICEDESC" = "$service.name$"
    "HOSTALIAS" = "$host.display_name$",
    "HOSTADDRESS" = "$address$",
    "SERVICESTATE" = "$service.state$",
    "LONGDATETIME" = "$icinga.long_date_time$",
    "SERVICEOUTPUT" = "$service.output$",
    "NOTIFICATIONAUTHORNAME" = "$notification.author$",
    "NOTIFICATIONCOMMENT" = "$notification.comment$",
	"HOSTDISPLAYNAME" = "$host.display_name$",
    "SERVICEDISPLAYNAME" = "$service.display_name$",
    "USEREMAIL" = "$user.email$"
  }
}

The command attribute in the mail-service-notification command refers to the following shell script. The macros specified in the env array are exported as environment variables and can be used in the notification script:

#!/usr/bin/env bash
template=$(cat <<TEMPLATE
***** Icinga  *****

Notification Type: $NOTIFICATIONTYPE

Service: $SERVICEDESC
Host: $HOSTALIAS
Address: $HOSTADDRESS
State: $SERVICESTATE

Date/Time: $LONGDATETIME

Additional Info: $SERVICEOUTPUT

Comment: [$NOTIFICATIONAUTHORNAME] $NOTIFICATIONCOMMENT
TEMPLATE
)

/usr/bin/printf "%b" $template | mail -s "$NOTIFICATIONTYPE - $HOSTDISPLAYNAME - $SERVICEDISPLAYNAME is $SERVICESTATE" $USEREMAIL

While it's possible to specify the entire notification command right in the NotificationCommand object it is generally advisable to create a shell script in the /etc/icinga2/scripts directory and have the NotificationCommand object refer to that.

Event Commands

Unlike notifications event commands are called on every service state change if defined. Therefore the EventCommand object should define a command line evaluating the current service state and other service runtime attributes available through runtime vars. Runtime macros such as $SERVICESTATETYPE$ and $SERVICESTATE$ will be processed by Icinga 2 helping on fine-granular events being triggered.

Common use case scenarios are a failing HTTP check requiring an immediate restart via event command, or if an application is locked and requires a restart upon detection.

EventCommand objects require the ITL template plugin-event-command to support native plugin based checks.

When the event command is triggered on a service state change, it will send a check result using the process_check_result script forcibly changing the service state back to OK (-r 0) providing some debug information in the check output (-o).

object EventCommand "plugin-event-process-check-result" {
  import "plugin-event-command"

  command = [
    PluginDir + "/process_check_result",
    "-H", "$host.name$",
    "-S", "$service.name$",
    "-c", LocalStateDir + "/run/icinga2/cmd/icinga2.cmd",
    "-r", "0",
    "-o", "Event Handler triggered in state '$service.state$' with output '$service.output$'."
  ]
}

Command Arguments

By defining a check command line using the command attribute Icinga 2 will resolve all macros in the static string or array. Sometimes it is required to extend the arguments list based on a met condition evaluated at command execution. Or making arguments optional - only set if the macro value can be resolved by Icinga 2.

object CheckCommand "check_http" {
  import "plugin-check-command"

  command = PluginDir + "/check_http"

  arguments = {
    "-H" = "$http_vhost$"
    "-I" = "$http_address$"
    "-u" = "$http_uri$"
    "-p" = "$http_port$"
    "-S" = {
      set_if = "$http_ssl$"
    }
    "-w" = "$http_warn_time$"
    "-c" = "$http_critical_time$"
  }

  vars.http_address = "$address$"
  vars.http_ssl = false
}

The example shows the check_http check command defining the most common arguments. Each of them is optional by default and will be omitted if the value is not set. For example if the service calling the check command does not have vars.http_port set, it won't get added to the command line. If the vars.http_ssl custom attribute is set in the service, host or command object definition, Icinga 2 will add the -S argument based on the set_if option to the command line. That way you can use the check_http command definition for both, with and without SSL enabled checks saving you duplicated command definitions.

Details on all available options can be found in the CheckCommand object definition.

Notifications

Notifications for service and host problems are an integral part of your monitoring setup.

When a host or service is in a downtime, a problem has been acknowledged or the dependency logic determined that the host/service is unreachable, no notirications are sent. You can configure additional type and state filters refining the notifications being actually sent.

There are many ways of sending notifications, e.g. by e-mail, XMPP, IRC, Twitter, etc. On its own Icinga 2 does not know how to send notifications. Instead it relies on external mechanisms such as shell scripts to notify users.

A notification specification requires one or more users (and/or user groups) who will be notified in case of problems. These users must have all custom attributes defined which will be used in the NotificationCommand on execution.

The user icingaadmin in the example below will get notified only on WARNING and CRITICAL states and problem and recovery notification types.

object User "icingaadmin" {
  display_name = "Icinga 2 Admin"
  enable_notifications = true
  states = [ OK, Warning, Critical ]
  types = [ Problem, Recovery ]
  email = "icinga@localhost"
}

If you don't set the states and types configuration attributes for the User object, notifications for all states and types will be sent.

You should choose which information you (and your notified users) are interested in case of emergency, and also which information does not provide any value to you and your environment.

An example notification command is explained here.

You can add all shared attributes to a Notification template which is inherited to the defined notifications. That way you'll save duplicated attributes in each Notification object. Attributes can be overridden locally.

template Notification "generic-notification" {
  interval = 15m

  command = "mail-service-notification"

  states = [ Warning, Critical, Unknown ]
  types = [ Problem, Acknowledgement, Recovery, Custom, FlappingStart,
            FlappingEnd, DowntimeStart,DowntimeEnd, DowntimeRemoved ]

  period = "24x7"
}

The time period 24x7 is shipped as example configuration with Icinga 2.

Use the apply keyword to create Notification objects for your services:

apply Notification "mail" to Service {
  import "generic-notification"

  command = "mail-notification"
  users = [ "icingaadmin" ]

  assign where service.name == "mysql"
}

Instead of assigning users to notifications, you can also add the user_groups attribute with a list of user groups to the Notification object. Icinga 2 will send notifications to all group members.

Notification Escalations

When a problem notification is sent and a problem still exists after re-notification you may want to escalate the problem to the next support level. A different approach is to configure the default notification by email, and escalate the problem via sms if not already solved.

You can define notification start and end times as additional configuration attributes making the Notification object a so-called notification escalation. Using templates you can share the basic notification attributes such as users or the interval (and override them for the escalation then).

Using the example from above, you can define additional users being escalated for sms notifications between start and end time.

object User "icinga-oncall-2nd-level" {
  display_name = "Icinga 2nd Level"

  vars.mobile = "+1 555 424642"
}

object User "icinga-oncall-1st-level" {
  display_name = "Icinga 1st Level"

  vars.mobile = "+1 555 424642"
}

Define an additional NotificationCommand for SMS notifications.

Note

The example is not complete as there are many different SMS providers. Please note that sending SMS notifications will require an SMS provider or local hardware with a SIM card active.

object NotificationCommand "sms-notification" {
   command = [
     PluginDir + "/send_sms_notification",
     "$mobile$",
     "..."
}

The two new notification escalations are added onto the host localhost and its service ping4 using the generic-notification template. The user icinga-oncall-2nd-level will get notified by SMS (sms-notification command) after 30m until 1h.

Note

The interval was set to 15m in the generic-notification template example. Lower that value in your escalations by using a secondary template or overriding the attribute directly in the notifications array position for escalation-sms-2nd-level.

If the problem does not get resolved or acknowledged preventing further notifications the escalation-sms-1st-level user will be escalated 1h after the initial problem was notified, but only for one hour (2h as end key for the times dictionary).

apply Notification "mail" to Service {
  import "generic-notification"

  command = "mail-notification"
  users = [ "icingaadmin" ]

  assign where service.name == "ping4"
}

apply Notification "escalation-sms-2nd-level" to Service {
  import "generic-notification"

  command = "sms-notification"
  users = [ "icinga-oncall-2nd-level" ]

  times = {
    begin = 30m
    end = 1h
  }

  assign where service.name == "ping4"
}

apply Notification "escalation-sms-1st-level" to Service {
  import "generic-notification"

  command = "sms-notification"
  users = [ "icinga-oncall-1st-level" ]

  times = {
    begin = 1h
    end = 2h
  }

  assign where service.name == "ping4"
}

First Notification Delay

Sometimes the problem in question should not be notified when the first notification happens, but a defined time duration afterwards. In Icinga 2 you can use the times dictionary and set begin = 15m as key and value if you want to suppress notifications in the first 15 minutes. Leave out the end key - if not set, Icinga 2 will not check against any end time for this notification.

apply Notification "mail" to Service {
  import "generic-notification"

  command = "mail-notification"
  users = [ "icingaadmin" ]

  times.begin = 15m // delay first notification

  assign where service.name == "ping4"
}

Notification Filters by State and Type

If there are no notification state and type filter attributes defined at the Notification or User object Icinga 2 assumes that all states and types are being notified.

Available state and type filters for notifications are:

template Notification "generic-notification" {

  states = [ Warning, Critical, Unknown ]
  types = [ Problem, Acknowledgement, Recovery, Custom, FlappingStart,
            FlappingEnd, DowntimeStart, DowntimeEnd, DowntimeRemoved ]
}

If you are familiar with Icinga 1.x notification_options please note that they have been split into type and state, and allow more fine granular filtering for example on downtimes and flapping. You can filter for acknowledgements and custom notifications too.

Downtimes

Downtimes can be scheduled for planned server maintenance or any other targetted service outage you are aware of in advance.

Downtimes will suppress any notifications, and may trigger other downtimes too. If the downtime was set by accident, or the duration exceeds the maintenance, you can manually cancel the downtime. Planned downtimes will also be taken into account for SLA reporting tools calculating the SLAs based on the state and downtime history.

Downtimes may overlap with their start and end times. If there are multiple downtimes triggered for one object, the overall downtime depth will be more than 1. This is useful when you want to extend your maintenance window taking longer than expected.

Fixed and Flexible Downtimes

A fixed downtime will be activated at the defined start time, and removed at the end time. During this time window the service state will change to NOT-OK and then actually trigger the downtime. Notifications are suppressed and the downtime depth is incremented.

Common scenarios are a planned distribution upgrade on your linux servers, or database updates in your warehouse. The customer knows about a fixed downtime window between 23:00 and 24:00. After 24:00 all problems should be alerted again. Solution is simple - schedule a fixed downtime starting at 23:00 and ending at 24:00.

Unlike a fixed downtime, a flexible downtime end does not necessarily happen at the provided end time. Instead the downtime will be triggered by the state change in the time span defined by start and end time, but then last a defined duration in minutes.

Imagine the following scenario: Your service is frequently polled by users trying to grab free deleted domains for immediate registration. Between 07:30 and 08:00 the impact will hit for 15 minutes and generate a network outage visible to the monitoring. The service is still alive, but answering too slow to Icinga 2 service checks. For that reason, you may want to schedule a downtime between 07:30 and 08:00 with a duration of 15 minutes. The downtime will then last from its trigger time until the duration is over. After that, the downtime is removed (may happen before or after the actual end time!).

Scheduling a downtime

This can either happen through a web interface or by sending an external command to the external command pipe provided by the ExternalCommandListener configuration.

Fixed downtimes require a start and end time (a duration will be ignored). Flexible downtimes need a start and end time for the time span, and a duration independent from that time span.

Triggered Downtimes

This is optional when scheduling a downtime. If there is already a downtime scheduled for a future maintenance, the current downtime can be triggered by that downtime. This renders useful if you have scheduled a host downtime and are now scheduling a child host's downtime getting triggered by the parent downtime on NOT-OK state change.

Recurring Downtimes

ScheduledDowntime objects can be used to set up recurring downtimes for services.

Example:

apply ScheduledDowntime "backup-downtime" to Service {
  author = "icingaadmin"
  comment = "Scheduled downtime for backup"

  ranges = {
    monday = "02:00-03:00"
    tuesday = "02:00-03:00"
    wednesday = "02:00-03:00"
    thursday = "02:00-03:00"
    friday = "02:00-03:00"
    saturday = "02:00-03:00"
    sunday = "02:00-03:00"
  }

  assign where "backup" in service.groups
}

Comments

Comments can be added at runtime and are persistent over restarts. You can add useful information for others on repeating incidents (for example "last time syslog at 100% cpu on 17.10.2013 due to stale nfs mount") which is primarly accessible using web interfaces.

Adding and deleting comment actions are possible through the external command pipe provided with the ExternalCommandListener configuration. The caller must pass the comment id in case of manipulating an existing comment.

Acknowledgements

If a problem is alerted and notified you may signal the other notification receipients that you are aware of the problem and will handle it.

By sending an acknowledgement to Icinga 2 (using the external command pipe provided with ExternalCommandListener configuration) all future notifications are suppressed, a new comment is added with the provided description and a notification with the type NotificationFilterAcknowledgement is sent to all notified users.

Expiring Acknowledgements

Once a problem is acknowledged it may disappear from your handled problems dashboard and no-one ever looks at it again since it will suppress notifications too.

This fire-and-forget action is quite common. If you're sure that a current problem should be resolved in the future at a defined time, you can define an expiration time when acknowledging the problem.

Icinga 2 will clear the acknowledgement when expired and start to re-notify if the problem persists.

Dependencies

Icinga 2 uses host and service Dependency objects for determing their network reachability. The parent_host_name and parent_service_name attributes are mandatory for service dependencies, parent_host_name is required for host dependencies.

A service can depend on a host, and vice versa. A service has an implicit dependency (parent) to its host. A host to host dependency acts implicit as host parent relation. When dependencies are calculated, not only the immediate parent is taken into account but all parents are inherited.

Notifications are suppressed if a host or service becomes unreachable.

A common scenario is the Icinga 2 server behind a router. Checking internet access by pinging the Google DNS server google-dns is a common method, but will fail in case the dsl-router host is down. Therefore the example below defines a host dependency which acts implicit as parent relation too.

Furthermore the host may be reachable but ping probes are dropped by the router's firewall. In case the dsl-router``ping4 service check fails, all further checks for the ping4 service on host google-dns service should be suppressed. This is achieved by setting the disable_checks attribute to true.

object Host "dsl-router" {
  address = "192.168.1.1"
}

object Host "google-dns" {
  address = "8.8.8.8"
}

apply Service "ping4" {
  import "generic-service"

  check_command = "ping4"

  assign where host.address
}

apply Dependency "internet" to Service {
  parent_host_name = "dsl-router"
  disable_checks = true

  assign where host.name != "dsl-router"
}

Custom Attributes

Using Custom Attributes at Runtime

Custom attributes may be used in command definitions to dynamically change how the command is executed.

Additionally there are Icinga 2 features such as the PerfDataWriter type which use custom attributes to format their output.

Tip

Custom attributes are identified by the 'vars' dictionary attribute as short name. Accessing the different attribute keys is possible using the '.' accessor.

Custom attributes in command definitions or performance data templates are evaluated at runtime when executing a command. These custom attributes cannot be used elsewhere (e.g. in other configuration attributes).

Here is an example of a command definition which uses user-defined custom attributes:

object CheckCommand "my-ping" {
  import "plugin-check-command"

  command = [
    PluginDir + "/check_ping",
    "-4",
    "-H", "$address$",
    "-w", "$ping_wrta$,$ping_wpl$%",
    "-c", "$ping_crta$,$ping_cpl$%",
    "-p", "$ping_packets$",
    "-t", "$ping_timeout$"
  ]

  vars.ping_wrta = 100
  vars.ping_wpl = 5
  vars.ping_crta = 200
  vars.ping_cpl = 15
  vars.ping_packets = 5
  vars.ping_timeout = 0
}

Custom attribute names used at runtime must be enclosed in two $ signs, e.g. $address$. When using the $ sign as single character, you need to escape it with an additional dollar sign ($$).

Runtime Custom Attributes Evaluation Order

When executing commands Icinga 2 checks the following objects in this order to look up custom attributes and their respective values:

  1. User object (only for notifications)
  2. Service object
  3. Host object
  4. Command object
  5. Global custom attributes in the Vars constant

This execution order allows you to define default values for custom attributes in your command objects. The my-ping command shown above uses this to set default values for some of the latency thresholds and timeouts.

When using the my-ping command you can override all or some of the custom attributes in the service definition like this:

object Service "ping" {
  host_name = "localhost"
  check_command = "my-ping"

  vars.ping_packets = 10 // Overrides the default value of 5 given in the command
}

If a custom attribute isn't defined anywhere an empty value is used and a warning is emitted to the Icinga 2 log.

Best Practice

By convention every host should have an address attribute. Hosts which have an IPv6 address should also have an address6 attribute.

Runtime Custom Attributes as Environment Variables

The env command object attribute specifies a list of environment variables with values calculated from either runtime macros or custom attributes which should be exported as environment variables prior to executing the command.

This is useful for example for hiding sensitive information on the command line output when passing credentials to database checks:

object CheckCommand "mysql-health" {
  import "plugin-check-command",

  command = PluginDir + "/check_mysql -H $address$ -d $db$",

  vars.mysql_user = "icinga_check",
  vars.mysql_pass = "password"

  env.MYSQLUSER = "$mysql_user$",
  env.MYSQLPASS = "$mysql_pass$"
}

Modified Attributes

Icinga 2 allows you to modify defined object attributes at runtime different to the local configuration object attributes. These modified attributes are stored as bit-shifted-value and made available in backends. Icinga 2 stores modified attributes in its state file and restores them on restart.

Modified Attributes can be reset using external commands.

Runtime Macros

Next to custom attributes there are additional runtime macros made available by Icinga 2. These runtime macros reflect the current object state and may change over time while custom attributes are configured statically (but can be modified at runtime using external commands).

Runtime Macro Evaluation Order

Custom attributes can be accessed at runtime using their identifier omitting the vars. prefix. There are special cases when those custom attributes are not set and Icinga 2 provides a fallback to existing object attributes for example host.address.

In the following example the $address$ macro will be resolved with the value of vars.address.

object Host "localhost" {
  import "generic-host"
  check_command = "my-host-macro-test"
  address = "127.0.0.1"
  vars.address = "127.2.2.2"
}

object CheckCommand "my-host-macro-test" {
  command = "echo \"address: $address$ host.address: $host.address$ host.vars.address: $host.vars.address$\""
}

The check command output will look like

"address: 127.2.2.2 host.address: 127.0.0.1 host.vars.address: 127.2.2.2"

If you alter the host object and remove the vars.address line, Icinga 2 will fail to look up $address$ in the custom attributes dictionary and then look for the host object's attribute.

The check command output will change to

"address: 127.0.0.1 host.address: 127.0.0.1 host.vars.address: "

The same example can be defined for services overriding the address field based on a specific host custom attribute.

object Host "localhost" {
  import "generic-host"
  address = "127.0.0.1"
  vars.macro_address = "127.3.3.3"
}

apply Service "my-macro-test" to Host {
  import "generic-service"
  check_command = "my-service-macro-test"
  vars.address = "$host.vars.macro_address$"

  assign where host.address
}

object CheckCommand "my-service-macro-test" {
  command = "echo \"address: $address$ host.address: $host.address$ host.vars.macro_address: $host.vars.macro_address$ service.vars.address: $service.vars.address$\""
}

When the service check is executed the output looks like

"address: 127.3.3.3 host.address: 127.0.0.1 host.vars.macro_address: 127.3.3.3 service.vars.address: 127.3.3.3"

That way you can easily override existing macros being accessed by their short name like $address$ and refrain from defining multiple check commands (one for $address$ and one for $host.vars.macro_address$).

Host Runtime Macros

The following host custom attributes are available in all commands that are executed for hosts or services:

Name Description
host.name The name of the host object.
host.display_name The value of the display_name attribute.
host.state The host's current state. Can be one of UNREACHABLE, UP and DOWN.
host.state_id The host's current state. Can be one of 0 (up), 1 (down) and 2 (unreachable).
host.state_type The host's current state type. Can be one of SOFT and HARD.
host.check_attempt The current check attempt number.
host.max_check_attempts The maximum number of checks which are executed before changing to a hard state.
host.last_state The host's previous state. Can be one of UNREACHABLE, UP and DOWN.
host.last_state_id The host's previous state. Can be one of 0 (up), 1 (down) and 2 (unreachable).
host.last_state_type The host's previous state type. Can be one of SOFT and HARD.
host.last_state_change The last state change's timestamp.
host.duration_sec The time since the last state change.
host.latency The host's check latency.
host.execution_time The host's check execution time.
host.output The last check's output.
host.perfdata The last check's performance data.
host.last_check The timestamp when the last check was executed.
host.num_services Number of services associated with the host.
host.num_services_ok Number of services associated with the host which are in an OK state.
host.num_services_warning Number of services associated with the host which are in a WARNING state.
host.num_services_unknown Number of services associated with the host which are in an UNKNOWN state.
host.num_services_critical Number of services associated with the host which are in a CRITICAL state.

Service Runtime Macros

The following service macros are available in all commands that are executed for services:

Name Description
service.name The short name of the service object.
service.display_name The value of the display_name attribute.
service.check_command The short name of the command along with any arguments to be used for the check.
service.state The service's current state. Can be one of OK, WARNING, CRITICAL and UNKNOWN.
service.state_id The service's current state. Can be one of 0 (ok), 1 (warning), 2 (critical) and 3 (unknown).
service.state_type The service's current state type. Can be one of SOFT and HARD.
service.check_attempt The current check attempt number.
service.max_check_attempts The maximum number of checks which are executed before changing to a hard state.
service.last_state The service's previous state. Can be one of OK, WARNING, CRITICAL and UNKNOWN.
service.last_state_id The service's previous state. Can be one of 0 (ok), 1 (warning), 2 (critical) and 3 (unknown).
service.last_state_type The service's previous state type. Can be one of SOFT and HARD.
service.last_state_change The last state change's timestamp.
service.duration_sec The time since the last state change.
service.latency The service's check latency.
service.execution_time The service's check execution time.
service.output The last check's output.
service.perfdata The last check's performance data.
service.last_check The timestamp when the last check was executed.

Command Runtime Macros

The following custom attributes are available in all commands:

Name Description
command.name The name of the command object.

User Runtime Macros

The following custom attributes are available in all commands that are executed for users:

Name Description
user.name The name of the user object.
user.display_name The value of the display_name attribute.

Notification Runtime Macros

Name Description
notification.type The type of the notification.
notification.author The author of the notification comment, if existing.
notification.comment The comment of the notification, if existing.

Global Runtime Macros

The following macros are available in all executed commands:

Name Description
icinga.timet Current UNIX timestamp.
icinga.long_date_time Current date and time including timezone information. Example: 2014-01-03 11:23:08 +0000
icinga.short_date_time Current date and time. Example: 2014-01-03 11:23:08
icinga.date Current date. Example: 2014-01-03
icinga.time Current time including timezone information. Example: 11:23:08 +0000
icinga.uptime Current uptime of the Icinga 2 process.

The following macros provide global statistics:

Name Description
icinga.num_services_ok Current number of services in state 'OK'.
icinga.num_services_warning Current number of services in state 'Warning'.
icinga.num_services_critical Current number of services in state 'Critical'.
icinga.num_services_unknown Current number of services in state 'Unknown'.
icinga.num_services_pending Current number of pending services.
icinga.num_services_unreachable Current number of unreachable services.
icinga.num_services_flapping Current number of flapping services.
icinga.num_services_in_downtime Current number of services in downtime.
icinga.num_services_acknowledged Current number of acknowledged service problems.
icinga.num_hosts_up Current number of hosts in state 'Up'.
icinga.num_hosts_down Current number of hosts in state 'Down'.
icinga.num_hosts_unreachable Current number of unreachable hosts.
icinga.num_hosts_flapping Current number of flapping hosts.
icinga.num_hosts_in_downtime Current number of hosts in downtime.
icinga.num_hosts_acknowledged Current number of acknowledged host problems.

Check Result Freshness

In Icinga 2 active check freshness is enabled by default. It is determined by the check_interval attribute and no incoming check results in that period of time.

threshold = last check execution time + check interval

Passive check freshness is calculated from the check_interval attribute if set.

threshold = last check result time + check interval

If the freshness checks are invalid, a new check is executed defined by the check_command attribute.

Check Flapping

The flapping algorithm used in Icinga 2 does not store the past states but calculcates the flapping threshold from a single value based on counters and half-life values. Icinga 2 compares the value with a single flapping threshold configuration attribute named flapping_threshold.

Flapping detection can be enabled or disabled using the enable_flapping attribute.

Volatile Services

By default all services remain in a non-volatile state. When a problem occurs, the SOFT state applies and once max_check_attempts attribute is reached with the check counter, a HARD state transition happens. Notifications are only triggered by HARD state changes and are then re-sent defined by the interval attribute.

It may be reasonable to have a volatile service which stays in a HARD state type if the service stays in a NOT-OK state. That way each service recheck will automatically trigger a notification unless the service is acknowledged or in a scheduled downtime.

External Commands

Icinga 2 provides an external command pipe for processing commands triggering specific actions (for example rescheduling a service check through the web interface).

In order to enable the ExternalCommandListener configuration use the following command and restart Icinga 2 afterwards:

# icinga2-enable-feature command

Icinga 2 creates the command pipe file as /var/run/icinga2/cmd/icinga2.cmd using the default configuration.

Web interfaces and other Icinga addons are able to send commands to Icinga 2 through the external command pipe, for example for rescheduling a forced service check:

# /bin/echo "[`date +%s`] SCHEDULE_FORCED_SVC_CHECK;localhost;ping4;`date +%s`" >> /var/run/icinga2/cmd/icinga2.cmd

# tail -f /var/log/messages

Oct 17 15:01:25 icinga-server icinga2: Executing external command: [1382014885] SCHEDULE_FORCED_SVC_CHECK;localhost;ping4;1382014885
Oct 17 15:01:25 icinga-server icinga2: Rescheduling next check for service 'ping4'

By default the command pipe file is owned by the group icingacmd with read/write permissions. Add your webserver's user to the group icingacmd to enable sending commands to Icinga 2 through your web interface:

# usermod -G -a icingacmd www-data

Debian packages use nagios as the default user and group name. Therefore change icingacmd to nagios.

External Command List

A list of currently supported external commands can be found here

Detailed information on the commands and their required parameters can be found on the Icinga 1.x documentation.

Event Handlers

Event handlers are defined as EventCommand objects in Icinga 2.

Unlike notifications event commands are called on every host/service execution if defined. Therefore the EventCommand object should define a command line evaluating the current service state and other service runtime attributes available through runtime macros. Runtime macros such as $service.state_type$ and $service.state$ will be processed by Icinga 2 helping on fine-granular events being triggered.

Common use case scenarios are a failing HTTP check requiring an immediate restart via event command, or if an application is locked and requires a restart upon detection.

Logging

Icinga 2 supports three different types of logging:

  • File logging
  • Syslog (on *NIX-based operating systems)
  • Console logging (STDOUT on tty)

You can enable additional loggers using the icinga2-enable-feature and icinga2-disable-feature commands to configure loggers:

Feature Description
debuglog Debug log (path: /var/log/icinga2/debug.log, severity: debug or higher)
mainlog Main log (path: /var/log/icinga2/icinga2.log, severity: information or higher)
syslog Syslog (severity: warning or higher)

By default file the mainlog feature is enabled. When running Icinga 2 on a terminal log messages with severity information or higher are written to the console.

Performance Data

When a host or service check is executed plugins should provide so-called performance data. Next to that additional check performance data can be fetched using Icinga 2 runtime macros such as the check latency or the current service state (or additional custom attributes).

The performance data can be passed to external applications which aggregate and store them in their backends. These tools usually generate graphs for historical reporting and trending.

Well-known addons processing Icinga performance data are PNP4Nagios, inGraph and Graphite.

Writing Performance Data Files

PNP4Nagios, inGraph and Graphios use performance data collector daemons to fetch the current performance files for their backend updates.

Therefore the Icinga 2 PerfdataWriter object allows you to define the output template format for host and services backed with Icinga 2 runtime vars.

host_format_template = "DATATYPE::HOSTPERFDATA\tTIMET::$icinga.timet$\tHOSTNAME::$host.name$\tHOSTPERFDATA::$host.perfdata$\tHOSTCHECKCOMMAND::$host.checkcommand$\tHOSTSTATE::$host.state$\tHOSTSTATETYPE::$host.statetype$"
service_format_template = "DATATYPE::SERVICEPERFDATA\tTIMET::$icinga.timet$\tHOSTNAME::$host.name$\tSERVICEDESC::$service.description$\tSERVICEPERFDATA::$service.perfdata$\tSERVICECHECKCOMMAND::$service.checkcommand$\tHOSTSTATE::$host.state$\tHOSTSTATETYPE::$host.statetype$\tSERVICESTATE::$service.state$\tSERVICESTATETYPE::$service.statetype$"

The default templates are already provided with the Icinga 2 feature configuration which can be enabled using

# icinga2-enable-feature perfdata

By default all performance data files are rotated in a 15 seconds interval into the /var/spool/icinga2/perfdata/ directory as host-perfdata.<timestamp> and service-perfdata.<timestamp>. External collectors need to parse the rotated performance data files and then remove the processed files.

Graphite Carbon Cache Writer

While there are some Graphite collector scripts and daemons like Graphios available for Icinga 1.x it's more reasonable to directly process the check and plugin performance in memory in Icinga 2. Once there are new metrics available, Icinga 2 will directly write them to the defined Graphite Carbon daemon tcp socket.

You can enable the feature using

# icinga2-enable-feature graphite

By default the GraphiteWriter object expects the Graphite Carbon Cache to listen at 127.0.0.1 on port 2003.

The current naming schema is

icinga.<hostname>.<metricname>
icinga.<hostname>.<servicename>.<metricname>

Status Data

Icinga 1.x writes object configuration data and status data in a cyclic interval to its objects.cache and status.dat files. Icinga 2 provides the StatusDataWriter object which dumps all configuration objects and status updates in a regular interval.

# icinga2-enable-feature statusdata

Icinga 1.x Classic UI requires this data set as part of its backend.

Note

If you are not using any web interface or addon which uses these files you can safely disable this feature.

Compat Logging

The Icinga 1.x log format is considered being the Compat Log in Icinga 2 provided with the CompatLogger object.

These logs are not only used for informational representation in external web interfaces parsing the logs, but also to generate SLA reports and trends in Icinga 1.x Classic UI. Futhermore the Livestatus feature uses these logs for answering queries to historical tables.

The CompatLogger object can be enabled with

# icinga2-enable-feature compatlog

By default, the Icinga 1.x log file called icinga.log is located in /var/log/icinga2/compat. Rotated log files are moved into var/log/icinga2/compat/archives.

The format cannot be changed without breaking compatibility to existing log parsers.

# tail -f /var/log/icinga2/compat/icinga.log

[1382115688] LOG ROTATION: HOURLY
[1382115688] LOG VERSION: 2.0
[1382115688] HOST STATE: CURRENT;localhost;UP;HARD;1;
[1382115688] SERVICE STATE: CURRENT;localhost;disk;WARNING;HARD;1;
[1382115688] SERVICE STATE: CURRENT;localhost;http;OK;HARD;1;
[1382115688] SERVICE STATE: CURRENT;localhost;load;OK;HARD;1;
[1382115688] SERVICE STATE: CURRENT;localhost;ping4;OK;HARD;1;
[1382115688] SERVICE STATE: CURRENT;localhost;ping6;OK;HARD;1;
[1382115688] SERVICE STATE: CURRENT;localhost;processes;WARNING;HARD;1;
[1382115688] SERVICE STATE: CURRENT;localhost;ssh;OK;HARD;1;
[1382115688] SERVICE STATE: CURRENT;localhost;users;OK;HARD;1;
[1382115706] EXTERNAL COMMAND: SCHEDULE_FORCED_SVC_CHECK;localhost;disk;1382115705
[1382115706] EXTERNAL COMMAND: SCHEDULE_FORCED_SVC_CHECK;localhost;http;1382115705
[1382115706] EXTERNAL COMMAND: SCHEDULE_FORCED_SVC_CHECK;localhost;load;1382115705
[1382115706] EXTERNAL COMMAND: SCHEDULE_FORCED_SVC_CHECK;localhost;ping4;1382115705
[1382115706] EXTERNAL COMMAND: SCHEDULE_FORCED_SVC_CHECK;localhost;ping6;1382115705
[1382115706] EXTERNAL COMMAND: SCHEDULE_FORCED_SVC_CHECK;localhost;processes;1382115705
[1382115706] EXTERNAL COMMAND: SCHEDULE_FORCED_SVC_CHECK;localhost;ssh;1382115705
[1382115706] EXTERNAL COMMAND: SCHEDULE_FORCED_SVC_CHECK;localhost;users;1382115705
[1382115731] EXTERNAL COMMAND: PROCESS_SERVICE_CHECK_RESULT;localhost;ping6;2;critical test|
[1382115731] SERVICE ALERT: localhost;ping6;CRITICAL;SOFT;2;critical test

Check Result Files

Icinga 1.x writes its check result files into a temporary spool directory where it reads these check result files in a regular interval from. While this is extremly inefficient in performance regards it has been rendered useful for passing passive check results directly into Icinga 1.x skipping the external command pipe.

Several clustered/distributed environments and check-aggregation addons use that method. In order to support step-by-step migration of these environments, Icinga 2 ships the CheckResultReader object.

There is no feature configuration available, but it must be defined on-demand in your Icinga 2 objects configuration.

object CheckResultReader "reader" {
  spool_dir = "/data/check-results"
}